#include "bits/stdc++.h" using namespace std; #define int int64_t void solve() { int n, k; cin >> n >> k; int a[n + 1]; for (int i = 1; i <= n; ++i) { cin >> a[i]; } vector<int> dif; for (int i = 2; i <= n; ++i) { dif.push_back(a[i] - a[i - 1] - 1); } int tot = a[n] - a[1] + 1; sort (dif.begin(), dif.end(), greater<int>()); int take = 0; for (int i = 0; i < k - 1; ++i) { take += dif[i]; } int ans = tot - take; cout << ans << '\n'; } signed main() { int t = 1; // cin >> t; for (int cs = 1; cs <= t; ++cs) { solve(); } return 0; }